Fuel injection system



April 7, l'ss J. BQ CLARK, V.1R FUEL. INJECTION SYSTEM Filed 'Julyl 1.1957 ENQ/NE RPM w w L/ Mu A rroRNEY.

United States Patent FUEL INJECTION SYSTEM John B. Clark, Jr., Ferndale,Mich., assignor to General Motors Corporation, Detroit, Mich., acorporation of Delaware Application July 1, 1957, Serial No. 669,252

8 Claims. (Cl. 12S-140) The present invention relates to a fuel meteringsystem for an internal combustion engine which utilizes an injector fordelivering a metered quantity of fuel to each cylinder of the engine.This invention is particularly directed to such an injector device inwhich the quantity of fuel supplied is determined by the speed of theengine as well as the load thereon. The density of the air in the intakemanifold is wholly a function of load, thus such density may be used asa control force in combination with engine speed for regulating thequantity of fuel supplied by said injector.

In an internal combustion engine it has been found that as the enginespeed increases beyond a given value the quantity of air inducted intothe cylinders is no longer proportional to the speed and begins to falloff. This Vdecrease in the quantity of inducted air results in adecrease in volumetric efiiciency of the engine. It is 'theorized thatthe decreased quantity of air inducted at the decrease in volumetricefficiency with increased engine speeds has been ignored. The failure toaccommodate the fuel supply system to a change in volumetric eiiiciencyresults in an unnecessarily rich fuel-air ratio with a consequent lossin economy as well as a loss in power performance.

It is the purpose of the present invention to provide a fuel injectionsystem in which the quantity of fuel supplied by the injector is maderesponsive to variations in volumetric efficiency.

The present fuel supply system provides a device for injecting a meteredquantity of fuel to each engine cylinder during each combustion cycle, apressure responsive means operatively connected to said device to varythe quantity of fuel output per cycle, means for creating a lcontrolpressure which is a function of and increase with engine speed, a meansfor modulating said control pressure in accordance with engine speed tocreate a vfresultant control pressure proportional to the volumetric`efficiency of the engine and further providing conduit means forconveying said resultant pressure to the pres- ,SUl' I'eSpOl'lSlVemeans.

The details of the present invention as well as other `objects andadvantages will be apparent from the descrip- 'tion which follows.

In the drawing: Figure 1 is a diagrammatic representation of a fuel {Ili'njection system embodyingA the present invention; and

, Figure 2 illustrates the relationship between volumetric any type ofspeed-density fuel injection system and the "ice present diagrammaticrepresentation is merely for the purpose of simply illustrating thebasic principles of the invention. An injector for each cylinder of theengine is shown generally at 10. The details of the injector, per se,constitute no part of the present invention and may be of any well knowntype such as that employing a plunger which is adapted to be pumped atengine speed to supply a metered charge of fuel for each combustioncycle of the associated cylinder. In this type of injector means isprovided for varying quantity of charge which the plunger may pump percycle. Typical of injectors which may be used are those shown in thecopending applications Serial Number 597,237, Groves, filed July 1l,1956, and Serial No. 512,448, Dolza, filed June 1, 1955, now abandoned.

In the present system a lever 12 is provided which is suitably connectedto the injector 10 to vary the quantity of the cyclic charge of theinjector and which lever is pivoted about an adjustable fulcrumindicated generally at 14. It is the means whereby lever 12 iscontrolled which constitutes the subject matter of the presentinvention. Before passing on to a description of the lever controlsystem it should be noted that fuel may be supplied to the injector 10by any suitable source of low pressure fuel through a make-up or supplypump 16 from a sump 18.

A pressure responsive device or servo is shown at 20, and includes a rod22 suitably articulated to lever 12 and centrally fixed at its other endto a diaphragm 24 peripherally supported within a casing 26. A spring 28is disposed in casing 26 and is adapted to bias against diaphragm 24 tomove the latter as well as rod 22 upwardly and pivot the control lever12 in a clockwise direction about its fulcrum 14. This type of movementof the control lever is in a direction to decrease the quantity of fuelsupplied by the injector It). The bottom side of the diaphragm 24 isopen to atmosphere. The upper side of the diaphragm 24 defines a chamber30 with the casing 26 and which chamber is adapted to be subjected to apressure bearing a given relation, infra, to engine speed and volumetricefficiency. In general, the pressure in chamber 30 increases with anincrease of engine volumetric efficiency so as to move the diaphragm 24and rod 22 downwardly to rotate the control lever in a counterclockwisedirection against the control force of spring 28 to increase thequantity of fuel supplied by injector 10.

In order to provide a basic control force or pressure which isproportional to engine volumetric efficiency, a first engine speedresponsive pump 32 is provided which has an intake conduit 34 leadingfrom the sump and an output passage 36 communicating with a reservoir38. Reservoir 38 includes an output conduit 40 communicating withdiaphragm chamber 30 in casing 26. Reservoir 38 also includes an orificeopening 42 which permits the fluid supplied by pump 32 to be returned tothe sump at a rate determined by a contoured adjustable control element44 which projects through the orifice 42. Assuming for the moment thatorifice 42 and element 44 together defined a fixed restriction, then acontrol force or pressure would be created by pump 32, for transmissionto diaphragm 24, which would be a function of and increase with enginespeed. However, as already noted such type of control pressure fails totake into account the decrease in volumetric efiiciency at increasedengine speeds due to the inability of the air induction system to supplyair in direct proportion to speed. The relationship of volumetricefficiency to engine speed is graphically illustrated by the family ofcurves shown in Figure 2. From these curves it is seen that at a givenmanifold vacuum, volumetric efficiency decreases above a :5 given speed.The orifice control element 44 is made adjustable so as to refiect thechange, eg. decrease at higher engine speeds, in volumetric efficiencyand to tailor the fuel supplied per combustion cycle to the decreasedquantity of air.

The shape or contour of the adjustable element 44 is made to provide atiow rate through the orifice 42 such that the pressure within thereservoir 38 will reflect the change in volumetric efficiency as enginespeed increases and further which change is manifested by a resultantcontrol force in conduit d@ which will cause the quantity of fuel percombustion cycle supplied by injector Ml to be tailored to the reducedquantity of air being supplied to each cylinder per combustion cycle atincreased engine speeds and to thereby maintain a substantially constantfuel-air ratio.

In order that the position of the adjustable element 44 be variable inaccordance with engine speed a control rod 45 is suitably fixed theretoand the latter connected at its other end to a diaphragm i8 mountedwithin a support casing 5d. A spring 52 is mounted in casing 5() and isadapted to bias diaphragm 43 and rod i6 in a downwardly direction tocause the element 44 to restrict the flow through orifice 42.

A second engine speed responsive pump 54 is provided which circulates afiuid through a closed circuit including an input passage portion 56 andan output passage portion 5S. The output passage 53 is in communicationwith the diaphragm chamber 69. A fixed orifice 62 is provided in theclosed control circuit between the input and output passages 56 and S3.Therefore, the pressure drop across orifice 62 is conveyed to thediaphragm i8 and since such pressure drop will be a function of andincrease with engine speed the position of the adjustable element ditwith respect to orifice 42 will be determined by engine Speed. As enginespeed increases, therefore, element di', is moved to increase flowthrough orifice di?. decreasing the pressure in passage l0 and therebyreducing the fuel supplied by injector l0 at higher engine speeds.

ln order that the control lever ft2 also refiect engine load, engineload responsive means 66 is provided to vary the position of theadjustable fulcrum ffl. Engine load responsive means 65 includes acasing 68 having a diaphragm 70 peripherally supported therein andcentrally secured to which diaphragm is a rod '72. Rod 72 is suitablyarticulated to a pivoted lever 7f3 which through a lever 76 connectswith the adjustable fulcrum f4. A spring member 78 is disposed in casing68 and biases the diaphragm 70 to the right so as to move the adjustablefulcrum i4 to the left. in this way the movement of the right end ismultiplied by the increased moment arm between the fulcrurn la and theinjector ifi increasing the quantity of fuel supplied by the injector.

A conduit 80 communicates with the casing 68 and is adapted to besuitably connected with the engine intake manifold whereby manifoldvacuum will act on the diaphragm 7i? in opposition to the force ofspring 7S. Thus as the manifold vacuum increases the diaphragm will bemoved to the left shifting tA e adjustable fulcrum f4 to the right todecrease quantity of fuel supplied by injector i@ consistent with thedecreased load on the engine as manifested by the increase in manifoldvacuum.

Thus the present fuel injection system provides a resultant injectorcontrol force which is proportional to engine sneed and load as modifiedto reflect the decreased volumetric efficiency which ccc at h. -r enginespeeds.

it is apparent that the inventive concept embodied in the presentinvention is not limited to the type of diagrammatic system used forillustrative purposes and further that the scope of the invention is tobe limited only by the hereinafter appended claims.

l claim:

l. A fuel metering system for an internal combustion engine comprisinginjector means for delivering metered quantities of fuei to eachcylinder of the engine, a control member for regulating the quantity ofmetered fuel supplied by the injector means, a servo for actuating saidmember, a first engine speed responsive pump, conduit meanscommunicating said pump and servo, an orifice associated with saidconduit means, said orifice being variable in accordance with changes involumetric efiiciency of the engine, pressure responsive means forcontrolling the size of said orifice, a second speed responsive pump,and conduit means communicating with said second pump and said pressureresponsive means to open said variable orifice in a fixed relation toengine speed.

2. A fuel metering system for an internal combustion engine comprisinginjector means for delivering metered quantities of fuel to eachcylinder of the engine, a control member for regulating the quantity ofmetered fuel supplied by the injector, a diaphragm, means operativelyconnecting said diaphragm and control member, spring means biasing saiddiaphragm to decrease the fuel output of the injector means, a firstengine speed responsive pump, conduit means communicating said pump anddiaphragm whereby the pressure of said pump opposes the force of saidspring, an o-rifice associated with said conduit means, said orificebeing variable in accordance with changes in volumetric efficiency ofthe engine, pressure responsive means for controlling the size of saidorifice, a second speed responsive pump, and conduit means communicatingsaid second pump and said pressure responsive means to open saidvariable orifice in a fixed relation to engine speed and to therebymodify the pressure output of the first pump.

3. A fuel metering system as set forth in claim 2 in which said variableorifice comprises a fixed opening in said first pump conduit means, acontoured element projecting within and movable relative to saidopening, a casing having a diaphragm therein, means connecting saiddiaphragm and contoured element, means biasing said element to restrictsaid opening, said second pump conduit means communicating with saiddiaphragm to cause the second pump pressure to increase fiow throughsaid opening as engine speed increases and to thereby modify thepressure output of the first pump.

4. A fuel metering system for an internal combustion engine comprisingan injector for delivering metered quantities of fuel to each cylinderof the engine, a control member for regulating the quantity of meteredfuel supplied by the injector, a servo for actuating said member, afirst engine speed responsive pump, conduit means communicating saidpump and servo, an orifice associated with said conduit means, saidorifice being variable in accordance with changes in volumetricefficiency of the engine, pressure responsive means for controlling thesize of said orifice, a second engine speed responsive pump, conduitmeans communicating said second pump and said pressure responsive meansto open said variable orice in a fixed relation to engine speed, andmanifold vacuum responsive means for modifying the operation of saidcontrol member whereby an increase in manifold vacuum will decrease thefuel output of said injector for a given engine speed.

5. A fuel metering system for an internal combustion engine comprisingan injector for delivering metered quantities of fuel to each cylinderof the engine, a control member for regulating the quantity of meteredlfuel supplied by the injector, an adjustable fulcrum for said member, aservo for pivoting said member about said fulcrum, a first engine speedresponsive pump, conduit means communicating said pump and servo, anorifice associated with said conduit means, said orifice being variablein accordance with changes in volumetric efficiency of the engine,pressure responsive means for controlling theV size of said orifice, asecond engine speed responsive pump, conduit means communicating saidsecond pump and said pressure responsive means to open said variableorifice to decrease the' resultant pressure in the conduit means forsaid first engine speed responsive pump as engine speed increases, adiaphragm operatively connected to said adjustable fulcrum, spring meansbiasing said diaphragm and fulcrum to a position permitting said servoto increase the fuel output of said injector, and conduit meanscommunicating manifold vacuum to said diaphragm permitting an increasein manifold vacuum to decrease the injector fuel output.

6. A fuel metering system as set forth in claim 5 in which said servocomprises a diaphragm, means operatively connecting said diaphragm andcontrol member, and spring means biasing said diaphragm to decrease thefuel output of the injector means, said first pump conduit meanscommunicating with said diaphragm enabling said first pump pressure tooppose the force of said spring means.

7. A fuel supply system for an internal combustion engine comprising adevice for injecting a quantity of fuel to each engine cylinder duringeach combustion cycle, pressure responsive means operatively connectedto said device to vary the quantity of fuel output per cycle, rst meansadapted to create a control pressure which is a function of enginespeed, second means for modulating said control pressure in accordancewith engine speed,

said second means reducing said control pressure in proportion todecreasing volumetric efciency of the engine, and conduit means forconveying said reduced control pressure to said pressure responsivemeans.

8. A fuel supply system for an internal combustion engine comprising adevice for injecting a quantity of fuel to each engine cylinder duringeach combustion cycle, pressure responsive means operatively connectedto said device to vary the quantity of fuel output per cycle, firstmeans adapted to create a control pressure which is a function of enginespeed, second means for modulating said control pressure in accordancewith engine speed, said second means reducing said control pressure inproportion to decreasing volumetric eiciency of the engine, conduitmeans for conveying said reduced control pressure to said pressureresponsive means, and manifold vacuum responsive means for modifying theoperation of said pressure responsive means causing an increase inmanifold vacuum to decrease the fuel output of said injecting device fora given engine speed.

No references cited.

, UNITED `STATES PATENT OFFICE CERTIFICATE OF `CORRECTION Patent No.2,880,714 April '7, 1959 Y John B'. Clark, ,In

It is hereby certified that error appears in the-printed specificationof the above numbered patent requiring correction and that the saidLetters Patent should read as corrected below.

Column 4, line 9, vafter "commmicating" strike', .out "with".

Signed and sealed this' 8th dey of Septembert 195? (SEAL) Attest:

KAEL E. MEINE ROBERT C. WATSON v Commissioner of Patents AttestingOficer

